The present invention relates to improved methods for preparing aryl hydrazines, aryl hydrazones, O-aryl hydroxylamines, N-aryl hydroxylamines, O-aryl oximes and the like which are useful intermediates and end products in pharmaceutical and agricultural applications. Certain products of the present invention are utilized in a novel entry into the classical Fischer indole synthesis.
Despite the recent successes with palladium-catalyzed cross-coupling reactions of Ar-X with amines, comparable couplings of aryl halides with hydrazines and the like have not been reported. Existing methods for the conversion of Ar-X to the corresponding aryl hydrazines often require harsh or restrictive reaction conditions and/or the presence of activating groups on the aromatic ring.
Thus there remains a need for an effective method of preparing a wide range of aryl hydrazines and the like under mild conditions and in high yields. There is a further need for an efficient catalytic system with high efficiencies and turnover numbers for the synthesis of these compounds.